proposal: simplify labels.Requirement creation

[filariow]

We can skip validations performed by labels.NewRequirement as operator is fixed, key is constant, and value is extracted from Custom Resources.

NewRequirement is the constructor for a Requirement. If any of these rules is violated, an error is returned:

1. The operator can only be In, NotIn, Equals, DoubleEquals, Gt, Lt, NotEquals, Exists, or DoesNotExist.
2. If the operator is In or NotIn, the values set must be non-empty.
3. If the operator is Equals, DoubleEquals, or NotEquals, the values set must contain one value.
4. If the operator is Exists or DoesNotExist, the value set must be empty.
5. If the operator is Gt or Lt, the values set must contain only one value, which will be interpreted as an integer.
6. The key is invalid due to its length, or sequence of characters. See validateLabelKey for more details.

The empty string is a valid value in the input values set. Returned error, if not nil, is guaranteed to be an aggregated field.ErrorList

SelectorFromSet does not perform any validation, which means the server will reject the request if the Set contains invalid values.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.36%. Comparing base (bd75cb2) to head (1538ea5).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #446      +/-   ##
==========================================
+ Coverage   78.14%   78.36%   +0.22%     
==========================================
  Files          41       41              
  Lines        2681     2672       -9     
==========================================
- Hits         2095     2094       -1     
+ Misses        491      487       -4     
+ Partials       95       91       -4     

Flag	Coverage Δ
unittests	78.36% <100.00%> (+0.22%)	⬆️

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[mfrancisc]

👍

[MatousJobanek]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alexeykazakov, filariow, MatousJobanek, mfrancisc

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